This invention relates generally to the field of food packaging and deals more particularly with a closure for a food container which provides clear signs of tampering when removed without authorization.
Cottage cheese, yogurt, ice cream and similar food products are typically packaged in relatively inexpensive disposable containers having removable lids. Normally, the container and lid are formed from either coated paperboard or injection molded thermoplastic materials such as polyethylene or polystyrene. The lid ordinarily fits tightly on top of the container so that it effectively seals the contents and yet can be easily removed and replaced. One problem with conventional food containers of this type is that the lid can be removed and the contents can be tampered with while the package is on a store shelf. After the lid has been replaced, there is no visible indication given that tampering has occurred.
Attempts have been made to provide tamper evident closures, as exemplified by U.S. Pat. Nos. 4,190,175 to Allen and 4,146,148 to Dwinell et al. These arrangements provide a tear away member such as a tear ring or diaphragm which must be torn away from the package in order to open it. Thus, a visual examination of the closure reveals whether or not it has been previously opened since the presence of the tear away member indicates a lack of tampering. After having been opened, the lid can be replaced to suitably enclose the contents of the container.
The closures shown in the aforementioned patents are so complicated and expensive that they are not practical for use on disposable containers such as those in which cottage cheese, yogurt, ice cream and similar foods are packaged. To my knowledge, a tamper evident closure which functions in a satisfactory manner and yet is sufficiently economical to be used on a food container of this type has never been available.